Newly Purchased 300D Questions.

[standard125r]

Just picked up an '80 300D w123. When I start it up it sounds like it's only hitting on 4 cylinders. It also hesitates slightly of idle. Second is the trans. It shifts if you let of the gas, or after it gets warm it seems to shift to often. I figure I've got a bad injector, and a bad modulater valve in the trans. Any other suggestions? Any place that will have the parts at a decent price?

This thing's a dog compared to my 16v.

[bill murrow]

Try replacing the fuel filters first. Probably needs that done anyway. While you're in there changing filters check the banjo fitting making sure thats not clogged. If that doesn't cure your problem then check your injectors. Another thing you may want to look at is the tank screen. A search will turn up the info on that and the other mentioned items.

Trannys aren't my thing so you're on your own there.

Parts are just as reasonable right here as anywhere else so check out fastlane.

Cheers,

Bill

[standard125r]

Thanks for the quick answer. I'll do the fuel filters tomorrow.

[bill murrow]

Sure, you're welcome.

I always start with the cheap easy stuff to see if that cures it. Let me know how you do.

Cheers,

Bill

[MTUpower]

You ought to have a black knob next to the stering wheel. It's the idle adjustment knob. It will raise and lower if the idle when working properly via a cable. Try that as in chicago winters you may need to let it warm up at a bit higher idle. If the engine is warm and you still feel it's only hitting on 4 cylinders then take a open end wrench and crack open one injector line near the injector. The engine ought to sound and act a bit different (rough) when you turn the securing nut counterclockwise- the fuel will now come out of the line- not into the cylinder. Tighten the line and the engine will smooth out again. Each cylinder ought to have the same effect. If one does not then you know that cylinder is not producing power somehow. Wear safety glasses while doing this as diesel my squirt out of the line in your face. Like the other person said- change your fuel filters first. The first thing you ought to do when buying a "new" mercedes is to change ALL the filters and then you have a baseline of when they were changed last. Ask away- that's why we are here. Good luck and keep at it.

[standard125r]

Thanks That is a great idea. I'll work on it tomorrow.

[DieselAddict]

Also make sure your glow plugs are working and that you're letting them do their job. A good 20 second glow can make all the difference. I don't understand your comment about the transmission: "It shifts if you let of the gas, or after it gets warm it seems to shift to often."

[standard125r]

I understand that the 300D has very long shift points. However, when I first start out in the morning I have to ease up on the gas to get a shift. As I approach 20miles or so of driving shifts seem to smooth out, but I begin to miss 3rd and go straight to 4th. Then it downshifts into 3rd.

[RichC]

Changing all three fuel filters in my car made a lot of difference.

The transmission is controlled by vacuum and a regulated vacuum leak.
Aparently a lot of the older cars have broken or disconnected lines.
Look for a vacuum wiring diagram on the drivers door post. Make sure yours is routed like the diagram.

There is a lot of information about the vacuum control for the transmission on this board, including some how-to's, just search around a bit.

I just got my tranny shifting half way decently, finally

Good Luck, and happy tinkering.
RichC

[standard125r]

Tweaked the modulator valve a little, and smoothed out the shifts. Hope to have the filters tomorrow.